.content{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
.btn_isshow{
    border: none;
    padding: 5px 10px;
    color: #fff;
    background: #000;
    border-radius: 5px;
    cursor: pointer;
    margin: 5px;
  }